In many systems, images of a head, which may comprise single images at different times, or stereoscopic pairs of images or other multi-view images, may be captured in one device and displayed on a different device for viewing by an observer. One non-limitative example is a system for performing teleconferencing between two telecommunications devices. In that case, each device may capture images of the observer of that device and transmit them to the other device over a telecommunications network for display and viewing by the observer of the other device. Digital representations other than images and/or complementary to images may also be captured, for example using depth measurements (e.g. using a time-of-flight camera).
When an image or other digital representation of a head is captured and displayed, the gaze of the head may not be directed at the observer. This may be caused for example by the gaze of the head not being directed at the sensing system (e.g. camera system) used to capture the digital representation (e.g. image), for example because a user whose head is imaged is observing a display in the same device as a camera system and the camera system is offset above (or below) that display. In that case, the gaze in the displayed images will be perceived to be downwards (or upwards). The human visual system has evolved high sensitivity to gaze during social interaction, using cues gained from the relative position of the iris and white sclera of other observers. Errors in the perceived gaze are disconcerting. For example in a system for performing teleconferencing, errors in the perceived gaze can create unnatural interactions between the users.
The present disclosure is concerned with processing techniques (e.g. image processing techniques) for adjusting digital representations (e.g. images) of a head region to correct the perceived gaze and/or to improve other aspects of a computer-generated display of the head region. The present disclosure is particularly concerned with implementing such processing techniques with minimal demands on computer hardware and/or power such that they provide results at or near input data frame rate or user feedback requirements.